That cost would vary greatly depending on what the repair is and whether or not the repair would be covered under warranty or not.

The best and most logical way to find out would be to take it to the Apple Store and ask them directly.
Asking that sort of question on an online forum will only bring you conjecture and "best guesses".

mac: a waterproof raincoat made of rubberized fabric
MAC: a data communication protocol sub-layer, also known as the Media Access Control
Mac: a brand name which covers several lines of personal computers designed, developed, and marketed by Apple Inc.